static VertsTris Subdivide(VertsTris orig)
{
var result = new VertsTris();
for (int i = 0; i < orig.tris.Count; i += 3)
{
var v1 = orig.verts[orig.tris[i + 0]];
var v2 = orig.verts[orig.tris[i + 1]];
var v3 = orig.verts[orig.tris[i + 2]];
// replace triangle by 4 triangles
var a = Vector3.Normalize((v1 + v2) / 2f);
var b = Vector3.Normalize((v2 + v3) / 2f);
var c = Vector3.Normalize((v3 + v1) / 2f);
result.AddTriangle(v1, a, c);
result.AddTriangle(v2, b, a);
result.AddTriangle(v3, c, b);
result.AddTriangle(a, b, c);
}
return(result);
}
public static Mesh Generate(int subdivisions = 0)
{
var t = (1.0f + Mathf.Sqrt(5.0f)) / 2.0f;
var icosahedron = new VertsTris {
// 12 vertices of a icosahedron
verts = new List <Vector3> {
new Vector3(-1, t, 0).normalized,
new Vector3(1, t, 0).normalized,
new Vector3(-1, -t, 0).normalized,
new Vector3(1, -t, 0).normalized,
new Vector3(0, -1, t).normalized,
new Vector3(0, 1, t).normalized,
new Vector3(0, -1, -t).normalized,
new Vector3(0, 1, -t).normalized,
new Vector3(t, 0, -1).normalized,
new Vector3(t, 0, 1).normalized,
new Vector3(-t, 0, -1).normalized,
new Vector3(-t, 0, 1).normalized
},
// 20 triangles of the icosahedron
tris = new List <int> {
// 5 faces around point 0
0, 11, 5,
0, 5, 1,
0, 1, 7,
0, 7, 10,
0, 10, 11,
// 5 adjacent faces
1, 5, 9,
5, 11, 4,
11, 10, 2,
10, 7, 6,
7, 1, 8,
// 5 faces around point 3
3, 9, 4,
3, 4, 2,
3, 2, 6,
3, 6, 8,
3, 8, 9,
// 5 adjacent faces
4, 9, 5,
2, 4, 11,
6, 2, 10,
8, 6, 7,
9, 8, 1
}
};
// refine triangles
for (int i = 0; i < subdivisions; i++)
{
icosahedron = Subdivide(icosahedron);
}
// Convert into a Unity mesh.
var mesh = new Mesh();
mesh.SetVertices(icosahedron.verts);
mesh.SetTriangles(icosahedron.tris, 0);
return(mesh);
}
